1. Field of the Invention
The present invention pertains to a method and system for treating sludges containing water, oils, and solids by a thermal drying and combustion process and including the addition of solid materials to the sludge. The process is also adapted for handling solids such as earth materials contaminated with hydrocarbon substances.
2. Background
There are several sources of oil sludges that develop in the production, transport and refining of hydrocarbon materials such as crude oil. Certain refinery processes and transport processes produce sludges comprising primarily water, crude oil and various solid fines such as scale, clay and sand. The solids can be small in size, such as in the range from 1 to 10 microns, and are thus difficult to separate from the oil and water through conventional separation process, including filtration or solvent extraction processes.
The aforementioned types of sludges are often difficult to handle by conventional waste treatment techniques since the various fractions of the crude oil may be volatile or tend to form coke or tar-like materials when subjected to prior art treatment processes. The material handling properties of tanker ballast sludges and refinery waste sludges, for example, interfere with the transfer of heat, resulting in clinkering or incomplete distillation and combustion.
A related problem in the handling of hydrocarbons in disposal and waste treatment processes pertains to earth-like materials which become contaminated with hydrocarbon substances, such as crude oils or partially or completely refined petroleum products. The decontamination of soils which have been subject to leakage from storage tanks, oil spills and other mishaps, presents at least two major interrelated problems, namely the effective removal of the hydrocarbons from the soil due to the wide range of properties hydrocarbons can exhibit when mixed with different soils and the dangers associated with treating the hydrocarbon substance depending on its volatility.
The present invention provides a process and system which is useful in treating oil sludges containing hydrocarbons of both naturally occurring crude petroleum and the like, as well as refined or partially refined petroleum products, which process and system is also adaptable to and advantageous for treating soils and other earth-like materials which have been contaminated or mixed with hydrocarbons.